The reduction of boron in permeate water is currently practiced by using a secondary pass reverse osmosis (RO) system whereby the pH of the feed is increased above pH 10 with a recovery of greater than 90%. These conditions lead to fouling of predominantly of magnesium hydroxide onto the membrane thus reducing its efficiency.

An investigation was carried out to study the fouling under conditions of high pH and recovery on a membrane. A new method was developed to study the deposition of magnesium hydroxide under dynamic conditions. The findings from this work show that there are significant differences in precipitation in the bulk solution phase and at the membrane surface. This method was used to demonstrate the efficacy of an antiscalant to control magnesium hydroxide precipitation under high pH and high recovery conditions.

Subject
Antiscalants, Water, Precipitation (solids), Hydroxides, Calcium carbonate, Bulk solution, Boron, Seawater, Scale deposition, Acidity, Scale formation, Magnesium, Deposit corrosion
Keywords:
Magnesium Hydroxide, Boron, Dynamic Test, Fouling, Reverse Osmosis, Second Pass, Antiscalant
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2008
Association for Materials Protection and Performance (AMPP)
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